The present invention relates generally to a descaling tool for use with a reciprocating hammer for removing foreign substances from metal, wood, stone, or the like. Examples of such devices can be seen in U.S. Pat. Nos. 1,004,6l7 to Archer; 2,356,314 to Gray et al.; 3,150,888 to Parker; 3,343,246 to Kelly et al.; 3,349,461 to Niedzwiecki; 3,359,611 to Kelley; 3,451,490 to Troike; 3,680,643 to Cameron et al.; and, 3,937,055 to Caruso et al. Each of these patents basically discloses a descaling tool including a plurality of elongated, rigid descaling needles. The descaling needles are typically formed of drill rod or similar tough, hard, elastic steel and have enlarged heads formed at one end thereof. The enlarged heads of the needles are positioned to engage a reciprocating hammer or piston, which is operable to impart axial motion to the needles. The scaling needles are individually mounted for reciprocal movement within a guide or housing which enables each needle to move freely within limits along a predetermined axis. A return spring is typically provided to force the enlarged heads of the needles into engagement with the reciprocating hammer or piston. The descaling operation is performed by the free ends of the needles being repeatedly propelled against the work surface to be cleaned.
While these devices are appropriate for removing scale from welds or cleaning generally planar surfaces, they are generally not suitable for intricate or irregular shapes or contours, such as keyways, gear teeth, or the like. In this respect, the needles of such devices are generally rigid, Which allows them to operate in conjunction with the aforementioned guide or housing. This rigidity, however, does not enable the needles to flex or conform to irregular or intricate shapes. Thus, the aforementioned devices are not particularly suitable for cleaning intricate surfaces having recesses or corners therein. Another problem with such devices is that the impact of the needles against the work surface cannot be controlled and is basically dependent upon the force of the pneumatic tool utilized. In other words, while a given descaling tool may be appropriate for removing heavy deposits on a generally planar surface, it is not suitable for use on detailed or intricate surfaces where a less forceful impact is required.
Several of the aforementioned patents, i.e. U.S. Pat. Nos. 3,359,611 to Kelly and 3,150,888 to Parker disclosed devices having guide sleeves around the needles encasing the return spring, which sleeves are axially adjustable to vary exposure of the needles. These devices, however, require that the sleeve be mechanically repositioned while the tool is inactive; and, more importantly, are provided, not so much to vary the impact of the needles, but rather to maintain their alignment and to vary the return force exerted on the needle housing or sleeve. In this respect, the sleeves or guides on these prior devices are primarily return spring retainers, and confined the ends of the needles in a predetermined pattern. Consequently, they did not provide a means for varying the intensity of the impact of the needles on the workpiece.
These and other problems are overcome by the present invention which provides a descaling device wherein the area of contact between the descaling needles and the workpiece, as well as the intensity of the impact of such needles against the workpiece may be easily adjustable during operation of the tool thereby providing a variable cleaning effect.